Access hole construction notably for tanks containing liquefied gas



ACCESS HOLE CONSTRUCTION NOTABLY FOR Jan. 2,1968 J. ALLEAUME 3,361,286

TANKS CONTAINING LIQUEFIED GAS Filed April 13, 1965 4 Sheets-Sheet 1 IN VENTOP TEA/v EAuME Arrow/5V5 Jan. 2, 1968 J. ALLEAUME 3,361,286 ACCESS HOLE CONSTRUCTION NOTABLY FOR TANKS CONTAINING LIQUEFIED GAS Filed April 15, 1965 4 sheets-sheet 2 INVENTO? JEAN ALLEAUHE Md, & M

ArroP/vay 4 Sheets-Sheet 3 INVENTDP JEAN ALLEAuME B M M Arrow/vans J. ALLEAUME ACCESS HOLE CONSTRUCTION NOTABLY FOR TANKS CONTAINING LIQUEFIED GAS Jan. 2, 1968 Filed April 13, 1965 Jan. 2, 1968 J. ALLEAUME' 3,361,286

' ACCESS HOLE CONSTRUCTION NOTABLY FOR TANKS CONTAINING LIQUEFIED GAS Filed April 13, 1965 16 lMve/vmP.

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ArroR/veys United States Patent 3,361,286 ACCESS HOLE CONSTRUCTEON NOTABLY FOR TANKS CONTAINING LIQUEFIED GAS Jean Alleaume, Saint Cloud, France, assignor to Technigaz, Paris, France, a body corporate under the laws of France Filed Apr. 13, 1965, Ser. No. 447,667 Claims priority, application France, Apr. 13, 1964, 970,761 22 Claims. (Cl. 220-14) ABSTRACT OF THE DISCLOSURE A storage tank comprising an inner, impervious, flexible, thin, corrugated, metal sheet wall spaced from an outer self-supporting wall structure with heat insulation filled therebetween for backing said inner wall, an access aperture, closable by a plug-like cover, and an impervious flexible and thin corrugated metal sheet element of the same thickness and nature as the inner wall and lining the aperture passageway to connect in sealing relationship said outer and inner walls and formed at least with spaced corrugations extending parallel with the aperture depth from the aperture outer edge and merging into corresponding corrugations of said inner wall.

The present invention is concerned essentially with an aperture-forming access device and the closing means thereof in the wall of a flexible, fluid tight tank subjected to stresses, deformations, strains (contractions and expansions) of thermal origin, as well as with the tanks thus equipped.

The transport and/or storage of liquefied gas at very low temperatures and under a pressure approximating the atmospheric value can be effected in flexible, fluid-tight and heat-insulated tanks, the cold liquid being contained in a volumetric capacity bounded by a Wall deriving its flexibility from two series of perpendicular corrugations and bearing against a firm support. Tanks constructed according to the same principle may be used to constitute sealed enclosures at high temperatures, such as the vessels of nuclear reactors.

To gain access to the inside of these enclosures for checking, inspecting, supervising, maintaining or repairing the enclosures themselves or the equipments existing therein, .or for introducing objects into these enclosures, apertures, of which the dimensions may vary within considerable limits, must be provided.

It is the essential object of this invention to solve this problem. In the case of tanks used for transporting and/ or storing liquefied gas at very low temperatures, these apertures are formed as a rule through a Wall constituting the ceiling or root of the tank. However, they may also be formed through any other walls object to simple adaptations.

The aperture must extend not only through the flexible, fluid-tight enclosure wall but also through the insulation and the external self-supporting and load bearing structure against which the flexible tank and/or the insulation is or are caused to bear.

To preserve the continuity of the fluid-tightness of this enclosure, the fluid-tight flexible enclosure must be connected to the self-supporting and load bearing structure supporting the lagging or like heat-insulation.

The connecting means must take due account of the characteristics of the self-supporting and load bearing structure, of the flexible enclosure and of actual working conditions. Thus:

The self-supporting and load bearing structure usually consists of construction steel for working at temperatures approximating the normal local environmental or external temperature;

being at local ambient temperature the self-supporting and load bearing structure is subjected only to contractions and expansions of very low amplitudes;

the self-supporting and load bearing structure is practically rigid;

the flexible fluid-tight enclosure is made from a material having satisfactory characteristics, considering the working temperatures contemplated;

at the temperatures prevailing in the fluid-tight enclosure, relatively important expansions or contractions may take place therein;

the fluid-tight enclosure is very flexible and therefore capable of absorbing thermal contractions or expansions without causing variations in its general geometrical dimensions, and without producing considerable strain in the material involved.

The connection between the self-supporting structure and the flexible fluid-tight enclosure may be obtained by means of a self-supporting rigid strong connecting element or by means of a flexible integrated connecting element.

In the first case, the connection between the flexible enclosure and the self-supporting element takes place in a region normally brought to a working temperature largely differing from the ambient atmospheric temperature. This form of connection is objectionable in that it blocks the corrugations of the flexible wall and introduces relatively high contractions at some locations of the flexible enclosure.

This invention is concerned more particularly with the second type of connection in the form of a flexible integrated connecting element adapted to avoid the production of local strain.

Other features of this invention will appear as the following detailed description proceeds with reference more particularly to an aperture formed in the ceiling or roof of a flexible heat-insulated enclosure intended for transporting liquefied gas at very low temperatures.

In the attached diagrammatic drawings, typical forms of embodiment of this invention are illustrated by Way of example. In the drawings:

FIGURE 1 illustrates, in fragmentary perspective view with parts broken away, the principle of a specific form of embodiment of the device of this invention, as applied to a tank roof structure;

FIGURE 2 is a fragmentary sectional view showing an alternative form of embodiment of the same device with a structure for supporting the ancillary devices, and with pipe passages and man-hole through the cover structure;

FIGURE 3 is a plan view from above showing separately the cover structure of FIGURE 2, .and

FIGURE 4 is a sectional view showing, on a smaller scale, another alternative form of embodiment of the device with a trussed girder for suspending the accessory or ancillary means therefrom.

An aperture of rectangular shape is formed in the inner fluid-confining, impervious, flexible sheet-like wall of said tank. The sides of the rectangle defining said aperture are substantially parallel to the directions, respectively, of the two systems of spaced parallel corrugations, ribs or folds, intersecting each other at substantially right angles. The four corners of this rectangular aperture are located each one inside and preferably in the middle or centrally of a rectangular, smooth or uncorrugated area bounded by the intersecting crests or raised portions of the corrugations of the two systems of corugations. i Y

A homologous aperture is formed through the insulation or lagging and through the outer self-supporting wall or structure 1. FIGURE 1 shows a typical example of one of the various possible constructions.

The sheet or plate material forming the self-supporting structure 1, in which the rectangular aperture is cut out, consists at least partially of steel having a satisfactory mechanical strength at the temperatures to which this material may be brought locally, and is preferably made from 18/8 type stainless steel stock to take advantage of the low heat conductivity of such material.

FIGURE 1 illustrates a typical example of a construction wherein the components designated by the reference numerals 1, 2 forming a reinforcing frame and a kind of neck tube, respectively, are constructed for example from stainless steel stock.

This aperture is accordingly surrounded and bounded by a reinforcing member 1, 7 of angle shaped or, boxgirder like section, made from a material having satisfactory properties at the temperatures to which it may be subjected locally in actual operation. The remaining or surrounding structure 1a, which is recessed with respect to the outer edge of the aperture, may consist of ordinary structural steel and is connected to the part 1 by means of a fluid-tight joint 1b which may for example be welded.

A connecting member 8 consisting of a sheet, foil or plate of same thickness and same material (for example aluminum, light alloy or preferably stainless steel, considering the low heat conductivity of this latter material) as the flexible wall sheeting of the inner shell or casing forming the fluid-confining tank proper, is provided with a single set of substantially parallel corrugations (extending vertically in this case) disposed at such a spacing from each other that these corrugations merge substantially at right angle into the corresponding corrugations, respectively, of the flexible and fluid-tight inner Wall sheeting in which the aperture is cut. This connecting member 8 is connected at its lower end to the tank inner sheet-metal wall or roof by means of at least one corner member 9 providing the desired flexible connection.

At the opposite or upper end, the connecting member 8 is welded to a relatively thin flat sheet or plate 10 of same material but free of corrugations and having formed therein an aperture of which the contour corresponds to that of the aforesaid connecting member. As this part is located outside, it is practically at the ambient temperature and the contractions and expansions are normally low enough to keep the stresses at a relatively low level even in the absence of corrugations.

The same fiat sheet-metal plate is bolted as at 3 with the interposition of a gasket on the reinforcing structure 7 (consisting of corner-, boxor like girder sections) mentioned hereinabove.

The detail of fastening designated by the reference numeral 3 in FIGURE 1 illustrates a typical example among many possible forms of embodiment.

FIGURE 2 illustrates another example selected among the many forms of embodiment which may be adopted. In this example the heat-insulating layer between the outer and inner tank walls extends up to the top or upper face 10 of the outer edge of the aperture, whereby the aforesaid members 1 and 10 may be constructed from ordinary structural steel. The connecting member 8 may comprise another series of corrugations (directed horizontally in this case) of which only one is shown, these corrugations lying in this case outside or lower than fitting surface area of the closing cover structure.

The connections are such that the connecting member 8 takes full advantage of the flexibility imparted by the corrugations in the portion subjected to expansions or contractions of thermal origin, said corrugations being blocked in a region at the ambient temperature where said expansions or contractions of thermal origin are relatively moderate.

The device for closing this aperture may be con= structed in several manners; thus, for example, an insulating panel 11 having a side contour conforming to the lateral surface of the volume defined by the connecting member 8 is provided and carried by a suitably stiffened fiat supporting plate 4 (see FIGURES 2 and 3) made from a suitable material such as aluminum, light alloy or stainless steel, and bolted on the reinforcing member 7 (corner-, boxor like girder section) surrounding the aperture formed in the external self-supporting structure.

This insulating panel may be constructed in several manners. Thus, it may consist of:

a rigid cellular insulating block properly cut and adhesively bonded to the supporting plate;

a plywood box filled with cellular or fibrous or powderlike insulation;

a fluid-tight box made from thin sheet-metal stock and comprising a flat thin bottom welded to a side wall similar to the connecting member used in lining the aperture, the corrugations of said side wall interfitting with those of the connecting member lining said aperture when the cover is in its closing position. At its opposite end or top, this box is welded to the supporting cover plate 4 bolted at 12 on the reinforcing memher 7 (of corner-, boxor like girder section) bounding the upper edge of the aperture in the outer selfsupporting structure.

FIGURE 1 illustrates a typical example of a similar construction wherein the reference numeral 4 designates the supporting cover plate and the reference numeral 5 designates the thin sheet-metal bottom of the box.

To avoid thermal leakages and the presence of cold spots on the supporting plate 4- closing the outer selfsupporting structure, an insulation gasket or packing acting as a joint 13 is disposed between the side walls of the closing plug-like member 11 and the connecting lining element 3 of the aperture, in the relatively small space or gap corresponding to the mounting clearance. This insulation will prevent the passage of convection streams and radiation.

Fastening of the accessories necessary for the liquid movements in the tanks (see FIGURES 2, 3 and 4). The apertures and closing devices described hereinabove may advantageously be used for permitting the passage of the pipe lines into the fluid-tight enclosures and/or supporting any ancillary equipments or accessories disposed inside the enclosure. The reference numeral 14 of FIGURE 2 designates a typical example of a passageway or duct mounting of this character. This detail shows for example how the passage of a pipe line may be con structed. The pipe line reinforced if desired with a socket or sleeve is welded directly to the supporting plate 4 and, in the case of a closing device constructed from thin sheetmetal stock, to the bottom 5 proper. Considering the nature and arrangement of the lagging or heat insulation disposed inside the box forming the plug-like cover portion, the thin bottom 5 thereof will easily sustain movements of which the amplitude corresponds to the strain or expansion applied to the pipe section disposed between the supporting plate 4 and the thin bottom 5 of the closing device.

Accessories such as a deep-well pump, level gage, ladder, etc. may also be supported by the closing device either directly by attachment to the supporting plate designated at 4 or through the medium of a rigid structure 15, for example made of tubular elements, secured in turn to the supporting plate. In FIGURE 4 the carrier structure 15 is extended inside the tank for example down to the bottom draining trap, sink or sump 16 thereof, in the form of a girder 17 preferably of trussed type which carries these accessories, notably the immersed pump 18.

In this case the cover comprises a man-hole 19 adapted to be closed by a detachable lid 20.

One of the advantages inherent with this specific mounting procedure resides in the possibility of prefabricating the closing device completely provided with all the accessories necessary for the storage tanks (pipe lines, pumps, ladders, level gage, etc.).

What I claim is:

1. A fluid-tight enclosure having a multiple-wall comprising at least one inner flexible, fluid impervious wall; an outer supporting structure entirely surrounding and spaced from said inner wall; at least one layer of heat insulating material entirely filling the intermediate space left between said outer structure and said inner wall, said inner wall bearing against said insulating material which is supported by said outer structure; said outer structure, said layer of insulating material and said inner wall being formed with at least one access aperture passing through the aggregate thickness of said multiple wall; fluid-tight, heat-insulated removable closure means for closing said aperture in sealed relation thereto, and a flexible, fluid-tight lining element, lining the wall defining said aperture and connecting in sealing relationship said outer structure and said inner wall, said inner wall being made from corrugated sheet material and said lining element consisting of corrugated sheet material of substantially the same thickness and nature as said inner wall and formed at least with corrugations extending substantially parallel with the depth direction of said aperture from the outer edge thereof and so spaced as to flexibly and tightly merge at one end thereof into corresponding corrugations of said inner wall, while being rigidly connected at their opposite end to said outer structure.

2. A device according to claim 1 wherein said inner wall is formed with two sets of spaced parallel corrugations the directions of which are substantially at right angles to each other so as to define therebetween substantially plane and rectangular areas, said access aperture being substantially rectangular with its sides substantially parallel to said perpendicular directions, re spectively, and having its corners located substantially centrally of four of said rectangular areas.

3. A device according to claim 1 wherein the edge of said aperture adjacent to said outer structure consists of a reinforcing frame the outer face of which is externally lined with a smooth plain plate conforming in shape to the contour of said aperture and rigidly connected to said lining element, said lining element being connected substantially at right angles to said inner wall through a flexible angle member.

4. A device according to claim 3 wherein said closure means consist of a stopper-like plug-shaped cover comprising an insulating panel to be inserted in and snugly fitting said aperture and substantially conforming to the cross-sectional contour of said lining element; and an outer supporting plate made integral with and projecting peripheral-1y outwards from said panel so as to close the aperture in said outer structure and to provide a flange for being releasably fastened to said outer structure.

5. A device according to claim 4 wherein said insulating panel consists of a fluid-tight, thin walled, flatbottomed, box-like plug the sides of which are complementary of those of said lining element and which is filled with insulating material.

6. A device according to claim 5 wherein a sealing joint gasket is interposed in the clearance space left between said panel and said lining element.

7. A device according to claim 6 wherein said closure means is formed with passage means for piping, fittings, mountings and fixture means adapted to project within said enclosure and attached to said closure means.

8. A device according to claim 7 wherein said closure means comprises supporting means for said mounting means, projecting into said enclosure and is formed with at least one man-hole fitted with a detachable lid.

'9. A device according to claim 8 wherein said inne-r wall is formed with two sets of spaced parallel corrugations the directions of which are substantially at right angles to each other so as to define therebetween substantially plane and rectangular areas, said access ape-rture being substantially rectangular with its sides substantially parallel to said perpendicular directions, respectively, and having its corners located substantially centrally of four of said rectangular areas.

10. An arrangement according to claim 1, comprising a reinforcing, substantially rigid frame provided outside on and integral with said outer structure and supporting at least partially said lining element.

11. An arrangement according to claim 10, wherein the outer edge of said aperture is defined by said frame, which is provided with an outer bearing surface the opening of which conforms in shape to the contour of said aperture and an apertured plate tightly connected to said lining element forming a kind of neck tube which extends up to the external inner edge of said frame and is joined to said inner wall.

12. An arrangement according to claim 11, wherein said frame is made from the same material as said inner wall and said lining element is applied at least partially in direct engaging relationship against the substantially flat inner face of said frame.

13. An arrangement according to claim 11, wherein said frame is made from the same material as said outer structure and said lining element is backed by a layer of insulating material provided between said lining element and said frame and extending between the insulation of said enclosure and said bearing surface of said frame.

14. An arrangement according to claim 13, wherein said lining element is connected substantially at right angles to said inner wall through at least one flexible angle member.

15. An arrangement according to claim 11, wherein said closure means consists of a stopper-like, plug-shaped cover construction comprising an insulating panel to be inserted in and snugly fitting said aperture and substantially conforming to the cross-sectional contour of said lining element; and an outer supporting plate made integral with and projecting peripherally outwards from said panel so as to close the aperture in said outer structure and to provide a flange for being releasably fastened to the latter, the sides of said insulating panel being of a corrugated pattern formed at least with groove-like elongated recessed depressions extending across the thickness of said panel to co-operate in interfitting relationship with corresponding complementary raised portions of corrugations formed in said lining element.

16. An arrangement according to claim 15, wherein said insulating panel consists of a fluid-tight, thin walled, fiat-bottomed, box-like plug member made of sheet metal, the sides of which are complementary of those of said lining element and which is filled with insulating material and integrally connected to said supporting plate.

17. An arrangement according to claim 15, wherein said panel consists of a substantially rigid solid block of cellular insulating material adhesively bonded to said supporting plate.

18. An arrangement according to claim 15, wherein said panel consists of a wooden casing filled with insulating material and adhesively bonded to said supporting plate.

19. An arrangement according to claim 15, wherein an insulating sealing joint gasket is interposed in a clearance space left between said panel and said lining element and between said supporting plate and the bearing surface of said frame.

20. An arrangement according to claim 15, where-in said cover is formed with through passageway means for piping, fittings, measuring instruments and appliances,

mountings and fixture means adapted to project within said tank and attached to said cover.

21. An arrangement according to claim 20, forming a storage tank for fluids, wherein said cover is formed with at least one man-hole fitted with a detachable lid and comprises supporting means for said mounting means, projecting into said tank and carrying the accessories required for operating said tank.

22. An arrangement according to claim 15, wherein said inner wall is formed with two sets of spaced parallel 10 corrugations the directions of which are substantially at right angles to each other so as to define therebetween substantially smooth, uncorrugated rectangular areas, said access aperture being substantially rectangular with its sides substantially parallel to said perpendicular directions, respectively, and having its corners located inside of four of said rectangular areas.

References Cited UNITED STATES PATENTS 3/1933 Gottschalk 220-10 5/1933 Prendergast 220-14 1/1944 Petri 220-14 1/1957 Bliss et al 114-74 6/1959 Morrison- 220-9 9/ 1962 Henry 220-9 5/1963 Brown 220-9 7/1963 Berta et a1. 220-14 2/1965 Perkins 312-214 FOREIGN PATENTS 5/1959 Russia.

THERON E. CONDON, Primary Examiner.

JAMES R. GARRETT, Examiner. 

